Microstructure Formation of Cement Mortars Modified by Superabsorbent Polymers

Abstract

The utilization of superabsorbent polymers (SAPs) in cement-based materials has been found to be a promising means of mitigating the autogenous propagation of shrinkage and cracks. On the other hand, the undesired effects of SAPs’ application on functional properties, including mechanical strength, microstructure formation, and the evolution of hydration heat are not properly understood, given the variety in SAPs’ characteristics. To contribute to the present state-of-the-art, cement mortars, modified with two grades of SAPs by dosages of 0.3%, 0.6%, and 0.9%, were designed and studied with emphasis on the relationship between the materials’ porosities and mechanical strengths. The obtained results are interpreted by scanning electron microscopy analysis and hydration heat evolution to elucidate the major changes and their driving factors. Besides the benefits associated with the mitigation of autogenous shrinkage, the achieved results point to an adverse effect of supplementation with SAP on mechanical strength at an early age, and an even more pronounced increase at a later age. The employed scanning electron microscopy images, together with mercury-intrusion porosimetry data, depict distortion in the material porosity as a result of the filling of formed voids and the closing of open ends by swelled hydrogels. Only the minor benefit of a greater cross-linking density was obtained by the formation of dense structures and the gains in mechanical strength therefrom.

The Effect of Superabsorbent Polymer on the Resilient and Plastic Strain Behavior of Cemented Soil under Traffic Load

“…It is often used as a water-retaining agent and water-saving agent in agriculture to improve soil performance [ 12 , 13 ]. In engineering, it is often used to improve self-drying properties of concrete and cement mortar [ 14 , 15 , 16 ]. Test results show that SAP has a positive effect on the unconfined strength and compressibility of soil with higher moisture content (such as dredged silt and excavated soft soil) [ 2 , 6 , 7 , 17 ].…”

Research on the Hydration and Mechanical Properties of NAC-Hardened Cement under Various Activation Methods

“…At present, adding mineral admixtures is one of the key technical ways to improve the durability of cementitious materials [5,6]. Nano-silicon-dioxide [7][8][9][10], nanocalcium-carbonate [11,12], nano-kaolin [13][14][15], and carbon nanotubes (CNTs) [16] are the major nano-scale admixtures used in cement-based materials. However, despite the unique advantages of nano-admixtures, it is difficult to prepare nano-silicon-dioxide and CNTs.…”